The present investigation compares the reducibility of self-fluxing sinters with theself-fluxing pellets made from iron ore concentrates at the same company. Laboratoryreduction tests were made with gases having compositions similar to blowing with blastswith or without injection of coke oven gas. The actual data of smelting of the self-fluxing sinters in a blast furnace are used to make necessary corrections for the resultsobtained from the laboratory tests, in order to estimate the possible coke rate of smeltingself-fluxing pellets without injection of coke oven gas in the same furnace. Estimation ofcoke rate is made by solution of two simultaneous equations, one for the coke requiredfor direct reduction of Fe_xO, MnO, P_2O_5 and SiO_2, heat supply and carburization, andthe other for that required for indirect reduction of Fe_xO multiplied by (1+ΔC％), plusthat required for carburization, where ΔC％ is the percentage ratio of the actual cokerate above the theoretical value to that required for indirect reduction of Fe_xO. Esti-mations are made for lowering ΔC in order to decrease the existing coke rate of smeltingof the self-fluxing sinters. The ΔC is considered to be a better measure for the efficiency of blase furnace opera-tion, in comparison with CO/CO_2 and coke rate.

FeO-Fe_2O_3-P_2O_5 CaO-P_2O_5FeO+Fe_2O_3 CaOFeO-Fe_2O_3CaO (FeO)FeO 1400℃ 4,7г/см~3±0,15г/см~325℃-5,85г/см~3 4,7г/см~3 FeO 1400℃FeO-Fe_2O_3-CaO-P_2O_5

An investigation on the oxidation of copper under an oxygen pressure of 76 mm Hgat 200-900℃ has been carried out. It is shown that, the oxidation of copper at 200-350℃ obeys a cubic law; at 400-550℃ the initial growth of the oxide layer is para-bolic, but departure from this law is evident at a later stage and the rate of oxidationbecomes increasingly smaller; in the temperature range of 600-900℃, however, the para-bolic rate law applies for the whole period of oxidation. From the results obtained be-tween 600℃ and 900℃, an activation energy of oxidation of 30,700 cal/mol has beenfound. The surface scale of copper is shown to be consisted of two layers, the outer layeris made of small-grained CuO whereas the inner one is composed of coarse-grained Cu_2Owith a somewhat open texture. From 300℃ to 550℃, the surface scaling exhibits arugged appearance, with the degree of ruggedness increasing with increased time andtemperature of oxidation. At 600℃ and 650℃, the scaling surface has been observedto be covered with rather dense CuO whiskers. Under the examination of electronmicroscope the oxide whiskers generally remain erect and straight, but a few of themappear to fall suddenly into a tangled bush under the action of the electron beam. Itwould appear that not all of the oxide whiskers are as perfect as is generally believed tobe dislocation-free single crystals. The different oxidation behaviors of copper at the different temperatures as observedare discussed in the light of surface morphology and gross defects such as cracks andcavities which may be present in the oxide layer. Moreover, on the assumption of Frank'smechanism of whisker growth, an explanation of the possibility of the presence of imper-fectly structured CuO whiskers is given.

The experimental details of the determination of diffusion coefficients by the"residual activity" method are described. The possible sources of errors are discussed.The diffusion coefficient of Co~(60) in copper single crystals determined by this method isgiven as D=0.84 exp (-52,100/RT) cm~2/sec which is in good agreement with the resultsof Macklietl and Sakamoto obtained by "sectioning method".

The self-diffusion coefficients of Fe~(55) and Co(60) in iron-50％ cobalt alloy in thetemperature range of 850-980℃ (α-region) have been measured by means of the"residual activity" method. The results are as follows: D_(Fe)= 0.26 exp(-55,600/RT) cm~2/sec, D_(Co)=14 exp(-65,000/RT) cm~2/sec. From quasi-chemical approach an approximate relationship between the activationenergies of self-diffusion in concentrated homogeneous solid solutions and those of self-diffusion and impurity diffusion in one of the components is derived as 7Q_(Fe)-3Q_(Co)=5Q_(Co)~0-Q_(Fe)~0. This relationship is found to be applicable in the Fe-50％ Co alloy (α-region).

Investigations have been carried out to study the process of strain ageing caused byoxygen in molybdenum by measuring the variation of the height of the internal frictionpeak with ageing-time. It was found that the peak height decreascs gradually and even-tually disappears with ageing-time both in quench-aged and in strain-aged specimens. Ifthe fully aged specimens were re-strained, the peak reappears immediately and its heightis higher than that of the quenched specimen. These processes may be repcatcd if thespecimens were further aged and strained. Systematic studies have been made on the kinetics of strain ageing and on the effectof deformation on the peak height. The results show that (1) the kinetics of strainageing follows Cottrell-Bilby's t~(2/3) relation; (2) the peak height increases with deforma-tion up to about 2.5％, and then decreases; (3) the decrease of the peak height cor-responds to an increase of yield stress. According to the above experimental results, it is believed that the decrease of thepeak height is associated with the segregation of oxygen atoms to dislocations duringageing. On the basis of this assumption, the dislocation density and the atmosphere con-centration were estimated.

The cold-rolling and recrystallization textures, after reductions of 70, 80 and 85 per-cent, of tungsten and niobium single crystals with (110) [001], (111) [112] and (320)[001] orientations have been investigated. The results are the same as those obtainedin Mo and Fe-Si single crystals. From the relationships between the recrystallization androlling textures, and the part played by the regions between slip bands in the recrystal-lization process, the mechanism of formation of the recrystallization textures has been dis-cussed. It is believed that the nucleation is a process of recrystallization in situ, andthe formation of recrystallization textures may be described generally as a process of re-crystallization in situ and preferred growth.

On the basis of our previous investigation, an Fe-Mn-Al steel containing 29.4％Mn, 3.8％ Al, 1.9％ Mo, 0.5％ V, 0.4％ W, 0.015％ B, 0.03％ N and 0.1％ C hasbeen studied systematically. Its workability is similar to that of 1Cr_(18)Ni_9Ti. The stress-rupture properties arecomparable to those of high Cr-Ni austenitic steels, such as ЭИ257Т (14％ Cr, 14％ Ni,2.15％ W, 0.5％ Mo, 0.5％ Ti, 0.1％ C) at 600°and 650℃ for several thousandhours. On ageing at temperatures from 600°to 750℃ for periods up to 9500 hours, ac-companied by changes in hardness, the following phases appeared with increasing ageingtime and temperature: γ V_4C_3, M_6C and AB_2 (Laves phase). The impact value de-creased from about 37 to 10 kg·m/cm~2 after 9500 hours at 650°and 700℃.

The formation of β_(Mn) type structure in several Fe-Mn-Al duplex steels with com-positions varying from 33 to 37％ Mn and 5 to 9％ Al has been systematically stud-ied by microscopic examination, X-ray diffraction analysis, microhardness indentation test,hardness measurement and impact test. The temperature range of transformation for (δ+γ) to β_(Mn) lies between 500°and1000℃. The lower temperature limit is lowered by the addition of Al and the upperlimit raised by Mn and Al. The morphology of β_(Mn) formed depends on the composition and heat treatment ofthe alloys. β_(Mn) needles are preferentially originated from δ/δ and δ/γ grain boundaries,ferrite grains, etc., and then grow into rods. At higher temperatures β_(Mn) forms inblocks along the δ/γ boundaries and later grows into δ-ferrite grains. A relief effect onthe polished surface has been observed after the formation of β_(Mn) needles and it is sug-gested that this β_(Mn) is formed by the bainitic transformation mechanism. It has beenfound that the impact value decreases and the hardness increases with increasing β_(Mn)content.

The nucleation process in the pearlite range is additive, except that holding in thelower pearlite range it tends to accelerate subsequent reaction at high temperature. Inthe bainite range, holding at a high temperature retards subsequent nucleation at a lowtemperature, while holding at a low temperature appears to accelerate subsequent nuclea-tion at a high temperature. The deviation from additivity depends upon difference be-tween the temperatures involved and the holding duration. It is suggested that the embryo of bainite is the same as that of martensite, i. e., ab. c. c. region surrounded by a dislocation loop. Holding in the lower pearlite range accelerates subsequent transformation to bainite.

For determining the total content of rare-earth elements in steels, a method con-sisting of extraction with ether, precipitation with oxalic acid and photometric determina-tion with arsenazo has been established. By dissolving the sample with a suitable elec-trolyte and separating the carbide involved, the phases of rare-earth elements presentedin steels may be also be determined quantitatively. The phenomenon of ionic inter-ference in the process of photometric determination has been observed, and a method toprevent it from occuring has been proposed. Furthermore, some important aspects ofoperations such as the dissolution of sample are discussed. The present method may beused to determine the content of rare-earth elements in common alloy steels not con-taining nickel, and the error is less than ±10％.

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